Upgrading to 9" rear

[BK_GrandMarquis]

OK, found out that from Quaife that their 8.8/28 for a SVT Cobra with IRS will not work with a solid rear axle. So my next option comes with another bunch of questions.

What is required to do a 9" differential upgrade. I know I will need new axles. I'll need a new ring and pinion, right? Will the 9" diff. slide right in or do I need a new housing? Do i need a new diff cover? Is the drive shaft an issue?


Thanks

[Marauder8]

OK, found out that from Quaife that their 8.8/28 for a SVT Cobra with IRS will not work with a solid rear axle. So my next option comes with another bunch of questions.

What is required to do a 9" differential upgrade. I know I will need new axles. I'll need a new ring and pinion, right? Will the 9" diff. slide right in or do I need a new housing? Do i need a new diff cover? Is the drive shaft an issue?


Thanks
Big, big task to convert to 9". Entirely different housing. I Believe you can one custom made for your car. Browse the web and you will find specialty Rear Axle shops.

[DEFYANT]

Ummm, why do you want to do this?

[jakdad]

OK, found out that from Quaife that their 8.8/28 for a SVT Cobra with IRS will not work with a solid rear axle. So my next option comes with another bunch of questions.

What is required to do a 9" differential upgrade. I know I will need new axles. I'll need a new ring and pinion, right? Will the 9" diff. slide right in or do I need a new housing? Do i need a new diff cover? Is the drive shaft an issue?


Thanks Talk to these guys.
http://www.currieenterprises.com/
If they have them, the rear housing will have proper brackets for mounting and alignment. Their housing would make it a lot easier installation.

[cyclone03]

OK, found out that from Quaife that their 8.8/28 for a SVT Cobra with IRS will not work with a solid rear axle. So my next option comes with another bunch of questions.

What is required to do a 9" differential upgrade. I know I will need new axles. I'll need a new ring and pinion, right? Will the 9" diff. slide right in or do I need a new housing? Do i need a new diff cover? Is the drive shaft an issue?


Thanks

Flame suit on for me,but here goes....


The only differents I know of between solid and IRS diffs are the snap ring retainer ring machined into the IRS diff side gears.This prevents non IRS diffs replacing IRS diffs,but they work the other way around.

I have no idea why Qauife would'nt know this.
Do they have an application for a 1986-2004 Mustang GT? Same thing.

[Joe Walsh]

To be blunt...Don't Bother....It would cost more money to fit a 9" rear under your MM/GM than it would to call DTS (Drive Train Specialists) or Mark Williams Enterprises and have them build a 'bullet-proof' 8.8" rear that will bolt in with no problems. Unless you are running un-godly amounts of HP and a manual transmission a properly prepped 8.8" rear will take the abuse.

[jakdad]

Currie also builds bullet proof 8.8s but they still wont handle the torque and HP of a 9". Like Joe said, it's a money game any way you slice it. Currie can custom build a housing that will bolt up under your car and be flanged on the ends to accept MM brakes. I tell you all this because no one said it had to be cost effective. Good luck.

[BK_GrandMarquis]

Flame suit on for me,but here goes....


The only differents I know of between solid and IRS diffs are the snap ring retainer ring machined into the IRS diff side gears.This prevents non IRS diffs replacing IRS diffs,but they work the other way around.

I have no idea why Qauife would'nt know this.
Do they have an application for a 1986-2004 Mustang GT? Same thing.

OK, I'm seem stumped now. A custom 9" is more money than I wanted to spend on this project and Quaife does not make a model or any other Mustang. So it looks like I will be looking elsewhere for a differential.

Thanks for everyone's replies again.

[jakdad]

OK, I'm seem stumped now. A custom 9" is more money than I wanted to spend on this project and Quaife does not make a model or any other Mustang. So it looks like I will be looking elsewhere for a differential.

Thanks for everyone's replies again. Why not save some money and have the rear end in your car rebuilt. You can option a locker and 31 spline axles with whatever gear you want.

[BK_GrandMarquis]

Why not save some money and have the rear end in your car rebuilt. You can option a locker and 31 spline axles with whatever gear you want.

Yeah I could, but I was just trying to have this done before I start autocrossing this year. The work and money required just isn't what I was looking to do this year.

[FordNut]

Yeah I could, but I was just trying to have this done before I start autocrossing this year. The work and money required just isn't what I was looking to do this year.
For autocross you should stick with the 8.8" and maybe have it built. The 9" is a lot heavier and increasing unsprung weight hurts your handling. I think I understand now why you were looking into the 8.8" IRS setup. It would have to be all custom fabrication for mounts, since the IRS was never offered in a full frame car, only unibody.

[JACook]

OK, I'm seem stumped now. A custom 9" is more money than I wanted to spend on this project and Quaife does not make a model or any other Mustang. So it looks like I will be looking elsewhere for a differential. Is there a reason you only want Quaife? Quaife is just a particular flavor of Torsen, no? Ford Racing sells
both TrueTrack and Zexel Torsen units for the 8.8, for either 28 or 31 spline axles. 'Bout $500 last I looked.

[BK_GrandMarquis]

Is there a reason you only want Quaife? Quaife is just a particular flavor of Torsen, no? Ford Racing sells
both TrueTrack and Zexel Torsen units for the 8.8, for either 28 or 31 spline axles. 'Bout $500 last I looked.

They have a good name with BMWs and racing. They are covered under warranty even if raced. I'm now looking into the other torsen type brands.

[cyclone03]

With your Autocrossing goals in mind Installing 9" housing ends on an 8.8 is a very good up grade,along with 31 spline axles.
I see ultimate HP is not your goal so a modded 8.8 maybe the way to go.An 8.8 has less intermal friction while running due to the pinion placement over a 9".

Now if you can't get the diff you want for an 8.8 your path is set.

Have you checked with Steeda , Saleen or Kenny Brown for this diff?
One of them my have a propriatory listing on that part so you cant buy it dirrect.

[BK_GrandMarquis]

With your Autocrossing goals in mind Installing 9" housing ends on an 8.8 is a very good up grade,along with 31 spline axles.
I see ultimate HP is not your goal so a modded 8.8 maybe the way to go.An 8.8 has less intermal friction while running due to the pinion placement over a 9".

Now if you can't get the diff you want for an 8.8 your path is set.

Have you checked with Steeda , Saleen or Kenny Brown for this diff?
One of them my have a propriatory listing on that part so you cant buy it dirrect.

Haven't checked with Steeda or Saleen but I'm pretty sure Kenny Brown uses an Auburn model.

[looking97233]

The major problem I see with the 9" swap would be the watts link. The watts link bolts to a stud sticking out the front of the center section of the 8.8. Whereas on the 9" the complete front of the center section housing comes off. The diff mounts into this then it gets bolted back in place. I'm sure someone could figure it out but...$$$.

[BK_GrandMarquis]

The major problem I see with the 9" swap would be the watts link. The watts link bolts to a stud sticking out the front of the center section of the 8.8. Whereas on the 9" the complete front of the center section housing comes off. The diff mounts into this then it gets bolted back in place. I'm sure someone could figure it out but...$$$.

Yeah, I've pretty much have resigned to the fact that I am not getting a Quaife differential. The SVT Cobra IRS Differential wasn't going to work but they had a 9" 31 spline. This turned out to be too involved to get this to work as well. So now I am just looking into another brand of Torsen. This makes things easier. I've already seen a couple that have options for a 8.8/28 spline on a solid rear axle.


Thanks again for everyones help. :up: